Quote:
Originally Posted by mikesouth
thats the point if he always knows and always pics one of the two doors that are NOT the right one the odds if you change are 2/3
if he doesnt know and randomly pics a door (and 33% of the time it has the car) then the odds are also 66%
there are variations
lets say he doesnt always off the choice, since he knows where the car is he can manipulate things....say you guess correctly and that is the only time he offers the choice or he only offers it if you guess wrong.
but those strategies would be easy to figure out
NOW it can be shown that if he always opens a door when the contestant is right and half the time when he's wrong--a perfectly rational approach--over the long haul the odds of the prize being behind Door #1 versus Door #2 are 50-50.
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http://www.bbc.co.uk/learningzone/cl...ned/11261.html
If you pick a door, before there are only 2 doors left, there is never a 50/50 chance at any point. Forget the fact there are only 2 doors LEFT, the fact is you are picking when there are more than 2 doors, so the odds are never 50/50, regardless if you whittle unopened doors from 3 (or a hundred, to grasp it) doors to 2 doors.